New production equipment is starting to become available that allows capturing and transmission of wide-angle, very high resolution video content. The processing of such media files requires high bandwidths (order of Gbps) and in order to exploit the full information in such video stream large video screens, typically the size of a video wall or a projection screen, should be used.
When watching video on a relatively small display, a user is not able not watch the entire video frame and all information contained therein. Instead, based on his or her preference a user will select a particular frame area, viewing angle or video resolution by interacting with the graphical user interface of the user equipment. Apart from the fact that current network capacity cannot handle the large bandwidth demands of these beyond-HD resolutions, it is simply not efficient to deliver content that will not be displayed on the screen anyway.
Mavlankar et al. describe in the article “An interactive region-of-interest video streaming system for online lecturing viewing”, proceeding of ICIP 2010, p. 4437-4440 a so-called tiled video system wherein multiple resolution layers of a video content file are generated using a server-based interactive Region-of-Interest encoder. Every layer is divided into multiple spatial segments or tiles, each of which can be encoded and distributed (i.e. streamed) independently from each other.
A video client may request a specific spatial region, a Region of Interest (ROI), and a server may subsequently map the ROI request to one or more segments and transmit a selected group of tiled streams to the client, which is configured to combine the tiled streams into one video. This way bandwidth efficient user-interactions with the displayed content, e.g. zooming and panning, may be achieved without requiring compromises with respect to the resolution of the displayed content. In such scheme however fast response and processing of the tiled streams is necessary in order to deliver quality of services and optimal user experience.
When implementing such services in existing large-scale content delivery schemes problems may occur. Typically, a content provider does not directly deliver content to a consumer. Instead, content is sent to a content distributor, which uses a content delivery network (CDN) to deliver content to the consumer. CDNs are not arranged to handle spatially segmented content. Moreover, known solutions for delivering spatially segmented content to a client (such as described in the article of Mavlankar) are not suitable for use with existing CDNs. Implementing a known server-based solution for resolving ROI requests in a CDN in which spatially segmented content may be stored at different locations, does not provide a scalable solution and may easily lead undesired effects such as overload and delay situations which may seriously compromise the realisation of such service.
Furthermore, the server-based ROI to tile mapping approach described by Mavlankar does not enable the possibility of a client accessing content through two separate access methods/protocols, such as a scenario in which some spatial segments (segment streams) may be received using broadcast or multicast as access technology (medium) and some other spatial segments may be received using for instance unicast as access technology. The server-based ROI mapping mechanism of Mavlankar will have no knowledge of the exact client-side capabilities for receiving segmented content via different access technologies and or access protocols.
Moreover, in order to handle and display a video stream on the basis of several spatially-segmented streams, specific functionality needs to be implemented in the client in order to enable the display of seamless video images on the basis of a number of spatial segment streams and to enable user-interaction with the displayed content.
Hence, there is a need in the prior art for efficient spatially-segmented content delivery to clients. In particular, there is a need for methods and systems for spatially-segmented content delivery systems which allow content delivery without requiring changes to conventional CDN infrastructure, and which may also provide a scalable and flexible solution for users interacting with high-resolution video content.